<!DOCTYPE html>
<html lang="en">
  <head>
    <meta charset="UTF-8" />
    <meta name="viewport" content="width=device-width, initial-scale=1.0" />
    <title>Document</title>
  </head>
  <body>
    <main>
      <div class="center-wrapper">
        <div class="center">center</div>
      </div>
      <div class="left">left</div>
      <div class="right">right</div>
    </main>
  </body>
  <style>
    main {
      background-color: blanchedalmond;
    }
    .center-wrapper {
      width: 100%;
      height: 100px;
    }
    main::after {
      content: "";
      display: block;
      clear: both;
    }
    .left,
    .right {
      width: 100px;
      height: 100px;
      background-color: aqua;
    }
    .center {
      margin: 0 100px;
    }
    div {
      /* border: 1px solid black; */
      background-color: gray;
      float: left;
    }
    .left {
      margin-left: -100%;
    }
    .right {
      margin-left: -100px;
    }
  </style>
</html>
